Avalanche Forecast
Regions: Mt Hood.
Mt Hood is the area where you are most likely to need to racthet back your plans on Monday. Avoid steeper terrain features with previous or newly forming firmer wind transported snow. New storm slab is possible in areas that recieve more than a few hours of rapidly accumulating snowfall.
Detailed Forecast
A weakening front and a weak surface low will move across the Northwest Sunday night. The main snow should be seen in the south Cascades and mainly at Mt Hood. Watch for a change Monday to moderate to strong W-NW alpine winds. Temperature fluctuations could be a little problematic. New snow by Monday morning could be in the 5-10 inch range but this is uncertain.
Keep an eye out for previous or newly forming wind slabs on Monday. Winds will have potentially load non-traditional aspects. If you see signs of winds transporting snow including plumes, drifts, and uneven snow surfaces, then avoid slopes where the wind loading is occurring.
New storm slab is possible in areas that recieve more than a few hours of rapidly accumulating snowfall.
Mt Hood is the area where you are most likely to need to ratchet back your plans on Monday.
Early season hazards still exist at lower elevations and especially around creek beds that are not filled in
Snowpack Discussion
SW winds in the teens have been seen at Meadows late Saturday and Sunday.
About 15-18 inches of light snow fell at Mt Hood in the 24 hours ending Saturday morning. Around a foot of recent snow now sits atop Monday’s freezing rain layer.
Moderate to strong WSW-WNW winds were seen Tuesday to Thursday. Further moderate SW winds were sDue to recent significant wind transport especially near and above treeline, height of snow can vary dramatically across terrain.
Observations
On Sunday the Meadows pro patrol reported wind on the ridges with new shallow wind slab expected there.
The Meadows pro patrol on Saturday reported now density snow to 6600 feet, no discernible failure planes in new snow, and new snow well bonded to old surfaces.
Backcountry observations from Thursday confirm wind redistribution of snow, with bare ridges and wind slabs on lee slopes observed.
Avalanche Problems
Wind Slabs
Release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..
Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.
Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 1
Storm Slabs
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1